The neatest trick to accomplish, when writing an intimate play, is to find that spark which ties the issues and personalties of a few people to something inherently a part of everyone. That very concept centers Stephen Karam’s “The Humans,” the Tony-winning play just opened with the entire original Broadway cast at the Ahmanson Theatre. Every single person, and virtually every single issue, has some element with which we are familiar. The problems and conflicts the characters have with each other are not on their own earth-shattering, but they are (as the playwright himself has said) the things which keep us up at night.

How these issues emerge, how they intertwine, and how these people – who essentially love each other – deal with them is the play. It is funny. It is wrenching. It leaves one with some curiosity about elements outside the frame. It is gently remarkable theater.

The Blake family has gathered for Thanksgiving at the New York apartment younger daughter Brigid is just moving into with her boyfriend Richard. Parents Eric and Deirdre come somewhat hesitantly from Scranton, bringing with them Eric’s mother – commonly referred to as Momo – who is in the later stages of Alzheimers Disease. Joining them is Brigid’s older sister, Aimee, a Philadelphia lawyer wounded by the breakup of her marriage, and by illness.

The apartment is almost a character – with a ground floor portion on entry and a stair down to a basement kitchen and dining area, and some very strange upstairs neighbor whose actions create enormous booming interruptions to the family proceedings. Trash compactors roar outside the lower door. The light bulbs seem to have a life of their own. And the furniture, with a couple of exceptions, has yet to arrive. As the family readies for and eats dinner, wrestles with issues of expectation, religion, aging, traditions large and small, and the nature of love, the audience is drawn in to sit with them, and to understand what it is driving some members’ lack of sleep.

Reed Birney has a feel for Eric’s combination of taciturn, teasing but loving care, and internal wrestling with a faceless fear. As Deirdre Jayne Houdyshell embodies that mother who fusses, radiates a specific sense of humor, wants to fix everyone’s problems, and yet wrestles with secrets of her own. Sarah Steele embraces Brigid’s combination of family loyalty and resistance, making her both a determinedly individual person and one connecting the varied personalities together.

Nick Mills gives Richard the semi-attached attitude of the observer looking in on a unit he is now becoming a part of. His attempts at connection are treated with the earnestness necessary to keep him on an edge but not rejectable. It’s a subtly tricky performance. Perhaps most remarkable is the performance of Lauren Klein as Momo. Late stage Alzheimers is tough to watch in real life, and even tougher to recreate, yet she makes the mumblings and particularly the moments of rage absolutely believable.

There is a reason this play won an award while still off-Broadway for ensemble performance. It is absolutely seamless, with characters as comfortable with each other as families are. Director Joe Mantello choreographs the thing as much as directs it, using David Zinn’s two-tiered set with real finesse. The sense of family, of separation and togetherness, of tension and softening, ebb and flow as such a gathering does. A nod also to Fitz Patton’s sound design, creating as it does the character of an upstairs neighbor we essentially never even see, but whose presence proves startlingly intrusive at oddly apt moments.

“The Humans” is fine, fine theater. It speaks to all the mistakes people who love each other make, all the expectations we have of each other and of ourselves, and yet does so by being small, intimate, and very character driven. This is not splashy fun, but it Is often very funny. This is not about the world’s problems, but it echoes a humanity full of flaws even if full of potential good. Its very familiarity is its strength, and will rest with you long after the play, which is performed without intermission, is done.